A Digital Atlas of the Guinea Pig Brain. A Comparative Study of qMRI at 3T with Histological Sections.

High quality magnetic resonance
images of the guinea pig brain have been collected using quantitative MRI
scanning techniques. This series of
images reveals a set of digital images of the guinea pig brain in sections that
are comparable to a set of images obtained with commonly used histological
sectioning and staining protocols. These
image sets lend themselves to the construction of a freely accessible and user
friendly digital atlas that can be labeled with anatomical structures and used
as a searchable database.

METHOD AND MATERIALS:

One healthy adult male guinea pig
was sub-lethally anesthetized and perfused with 4% formalin through the heart
in accordance with the IACUC approved protocol at the Mass Eye and Ear
Infirmary. The entire brain (still
within the cranial vault), was post-fixed for 2 hrs in 4% formalin, and then
removed into 0.01M phosphate buffered saline for one week. The specimen was then immobilized in a 2%
agarose block. Imaging was accomplished
using a z3D-mixed-TSE scanning protocol in a 3T clinical MRI scanner (Philips
Medical Systems, Cleveland OH). After Scanning was accomplished, the specimen
was removed from agarose, dissected from the cranial vault, and frozen
sectioned at 80um on a sliding microtome. Alternate sections were stained with
a Nissl stain, and an acetylcholinesterase
stain.

RESULTS:

Three sets of anatomical images
were converted to jpeg format, and multiple anatomical structures were labeled in order to make
comparisons.

CONCLUSION:

The quantitative magnetic resonance images (qMRI) provide an
anatomical image set which is comparable to the pervasive “gold standard”
histological data. These image sets lend themselves easily to the construction
of digital image sets which will be accessible, searchable and forms a valuable
resource to the research community. This pulse sequence and construction format also has the potential to be
applied to in vivo applications.